Ducati Monster Forum

Moto Board => Tech => Topic started by: Smokescreen on August 12, 2014, 05:01:05 PM

Title: losing rear brake pressure
Post by: Smokescreen on August 12, 2014, 05:01:05 PM
So there is no leak in my circuit, but my rear brake (S2R1K) once bled, will work for a day and be flat the next day.  I don't use the rear a lot, but I don't like not having it one bit. 

Ideas?

Has anybody experienced this?

Find a solution? 

Is there a rebuild kit for the piston somewhere someone maybe has a link for?
Title: Re: losing rear brake pressure
Post by: Dirty Duc on August 12, 2014, 05:29:50 PM
It can be difficult to get that last air bubble out of the rear brake line.
Title: Re: losing rear brake pressure
Post by: Smokescreen on August 12, 2014, 05:45:15 PM
I don't think it's a lingerer.  I vacuum bleed and have pressure when I'm done.  the brake works, then the next day it doesn't.  So I'm thinking either it's a leaky crush point, or it's the master cylinder/piston
Title: Re: losing rear brake pressure
Post by: ducpainter on August 12, 2014, 05:57:20 PM
Not uncommon for a Duc rear master to be junk.

No rebuild parts available in the US AFAIK.
Title: Re: losing rear brake pressure
Post by: Smokescreen on August 12, 2014, 06:11:29 PM
As far as I can tell, the rear brake is the Brembo PS 11 C.  I've found a rebuild kit in the UK and Germany, but nothing in USa yet. 
Title: Re: losing rear brake pressure
Post by: ducpainter on August 12, 2014, 06:49:30 PM
Quote from: Smokescreen on August 12, 2014, 06:11:29 PM
As far as I can tell, the rear brake is the Brembo PS 11 C.  I've found a rebuild kit in the UK and Germany, but nothing in USa yet. 
We're not smart enough to rebuild a hydraulic brake component. ;)
Title: Re: losing rear brake pressure
Post by: brad black on August 12, 2014, 07:24:57 PM
bleed it with the caliper raised, then with it off the disc pump the pads out and push them back a few times.  increase the freeplay at the piston pushrod.
Title: Re: losing rear brake pressure
Post by: SpikeC on August 13, 2014, 09:29:35 AM
 I rebuilt the rear master on my BMW without any problem.
Title: Re: losing rear brake pressure
Post by: Smokescreen on August 13, 2014, 08:13:05 PM
I'd still need to be certain that the master is a PS11c, or a PS11b, or something else altogether...
Title: Re: losing rear brake pressure
Post by: Speeddog on August 13, 2014, 08:55:36 PM
Quote from: SpikeC on August 13, 2014, 09:29:35 AM
I rebuilt the rear master on my BMW without any problem.

Which could easily be the case on our Brembo masters, *if* there were parts available.
Title: Re: losing rear brake pressure
Post by: SpikeC on August 13, 2014, 09:03:30 PM
 Well, it was a while ago........
Title: Re: losing rear brake pressure
Post by: Howie on August 13, 2014, 10:29:21 PM
Quote from: Smokescreen on August 13, 2014, 08:13:05 PM
I'd still need to be certain that the master is a PS11c, or a PS11b, or something else altogether...

AFIAK there are only two, PS11b and PS11 straight outlet, both come in black or gold.  Anyway, they are not that expensive new if you do not buy it from Ducati.  Contact Fred at  http://www.yoyodyneti.com/contact.aspx (http://www.yoyodyneti.com/contact.aspx)  and he will help you out.
Title: Re: losing rear brake pressure
Post by: ellingly on August 13, 2014, 11:44:13 PM
In terms of this, I sort of have similar but not as bad. Too lazy to throw a new master on and fix my ultimate cause.

In my case, a) you do have to lift the master up and bleed it as per what Brad says, otherwise you do end up with some irritating bubbles. but there's also my issue b) which is that the pushrod from the brake lever is a bit rusty, which has chewed into the seal which means there's perpetually a tiny air leak back through the push rod.

Now, I don't actually care that much about using the rear brake especially when riding really hard, so I live with it. I have a spare master and new pushrod I'll throw on one day. One day.
Title: Re: losing rear brake pressure
Post by: Speeddog on August 14, 2014, 10:12:48 AM
Quote from: howie on August 13, 2014, 10:29:21 PM
AFIAK there are only two, PS11b and PS11 straight outlet, both come in black or gold.  Anyway, they are not that expensive new if you do not buy it from Ducati.  Contact Fred at  http://www.yoyodyneti.com/contact.aspx (http://www.yoyodyneti.com/contact.aspx)  and he will help you out.

+1, as there's no rebuild kits.

You might try a new rubber seal and plastic elbow where the reservoir hose hooks to the master.
I've seen some annoying air leaks there.

Unfortunately, Yoyodyne is no longer a Brembo distributor.
Title: Re: losing rear brake pressure
Post by: ducpainter on August 14, 2014, 10:32:50 AM
Quote from: Speeddog on August 14, 2014, 10:12:48 AM
<snip>

Unfortunately, Yoyodyne is no longer a Brembo distributor.
That isn't very handy.

Who is now?
Title: Re: losing rear brake pressure
Post by: Speeddog on August 14, 2014, 11:42:47 AM
Quote from: ducpainter on August 14, 2014, 10:32:50 AM
That isn't very handy.

Who is now?

From the small amount I've been able to penetrate in the Brembo website, it appears that TAW is the only USA Brembo moto product distributor.

At this moment, their website 'fitment' utility does not work properly for Brembo applications.

If you know the Brembo part number you're looking for, you can find it.
Title: Re: losing rear brake pressure
Post by: ducpainter on August 14, 2014, 11:47:34 AM
Eric is a dealer for them.

He prolly has the part#'s covered.
Title: Re: losing rear brake pressure
Post by: Speeddog on August 14, 2014, 12:12:35 PM
Didn't know he was.

I'm sure he's got the part numbers.  :)
Title: Re: losing rear brake pressure
Post by: jduke on August 14, 2014, 12:42:07 PM
I think the Duc Shop in Atlanta is a Brembo distributor.